Advanced Curves (with drag interaction)

C4WorkSpace.m

//
//  C4WorkSpace.m
//  Examples
//
//  Created by Travis Kirton on 12-07-19.
//

#import "C4WorkSpace.h"

@interface C4WorkSpace ()
-(void)updateControlA;
-(void)updateControlB;
-(void)updateControlC;
@end

@implementation C4WorkSpace {
    C4Shape *bezierCurve, *quadraticCurve;
    C4Shape *controlA, *controlB, *controlC;
}

-(void)setup {
    //create the end points for the bezier curve
    CGPoint bezierEndPoints[2] = {
        CGPointMake(0.3f*self.canvas.width,self.canvas.height/3),
        CGPointMake(0.7f*self.canvas.width,self.canvas.height/3)
    };
    
    //create the control points for the bezier curve
    CGPoint bezierControlPoints[2] = {CGPointMake(32,32), CGPointMake(self.canvas.width-32,32)};
    
    //create the bezier curve
    bezierCurve = [C4Shape curve:bezierEndPoints controlPoints:bezierControlPoints];
    [self.canvas addShape:bezierCurve];

    //create the end points for the bezier curve
    CGPoint quadEndPoints[2] = {
        CGPointMake(0.3f*self.canvas.width,self.canvas.height*2/3),
        CGPointMake(0.7f*self.canvas.width,self.canvas.height*2/3)
    };

    //create the control point for the quadratic curve
    CGPoint quadControlPoint = self.canvas.center;
    quadControlPoint.y = self.canvas.height - 32;
    
    //create the bezier curve
    quadraticCurve = [C4Shape quadCurve:quadEndPoints controlPoint:quadControlPoint];
    [self.canvas addShape:quadraticCurve];
    
    //create 3 control shapes
    CGRect controlFrame = CGRectMake(0, 0, 44, 44);
    controlA = [C4Shape ellipse:controlFrame];
    controlB = [C4Shape ellipse:controlFrame];
    controlC = [C4Shape ellipse:controlFrame];
    
    //move control shapes points to the coordinates of the curve control points
    controlA.center = bezierControlPoints[0];
    controlB.center = bezierControlPoints[1];
    controlC.center = quadControlPoint;
    
    //style the control shapes
    controlA.lineWidth = controlB.lineWidth = controlC.lineWidth = 0.0f;
    controlB.fillColor = C4RED;
    controlC.fillColor = C4GREY;
        
    [self.canvas addShape:controlA];
    [self.canvas addShape:controlB];
    [self.canvas addShape:controlC];

    //add drag gestures to the control shapes
    [controlA addGesture:PAN name:@"panGesture" action:@"move:"];
    [controlB addGesture:PAN name:@"panGesture" action:@"move:"];
    [controlC addGesture:PAN name:@"panGesture" action:@"move:"];
    
    //listen for when the control shapes are moved and update the curves as needed
    [self listenFor:@"moved" fromObject:controlA andRunMethod:@"updateControlA"];
    [self listenFor:@"moved" fromObject:controlB andRunMethod:@"updateControlB"];
    [self listenFor:@"moved" fromObject:controlC andRunMethod:@"updateControlC"];
}

-(void)updateControlA {
    bezierCurve.controlPointA = controlA.center;
}

-(void)updateControlB {
    bezierCurve.controlPointB = controlB.center;
}

-(void)updateControlC {
    quadraticCurve.controlPointA = controlC.center;
}

@end